LEE- Raylı Sistemleri Mühendisliği-Yüksek Lisans
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ÖgePetri ağları ile otomatik tren koruma sistemi tasarımı(Lisansüstü Eğitim Enstitüsü, 2023-09-22)Demiryolu sinyalizasyon sistemlerinin kullanım amacı demiryolu trafiğini düzenlemek ve demiryolu taşımacılığın güvenliğini sağlamaktır. Demiryolu taşımacılığının gelişimine paralel olarak demiryolu sinyalizasyon sistemleri de gelişim göstermiştir. 1830'larda demiryolu sinyalizasyonu sinyal görevlilerinin kullandığı el sinyalleri ile sağlanmaktaydı.1860'larda mekanik sinyalizasyon cihazları (semafor ve mekanik sinyalizasyon) kullanımı artmıştır.1900'lerin başlarında mekanik sinyalizasyon sistemlerinin yerine elektromekanik sinyalizasyon sistemleri kullanılmaya başlanmıştır.1960'larda sinyalizasyon sistemlerine bilgisayar tabanlı kontrol ve izleme özellikleri eklenmiştir. Sinyalizasyon sistemlerinin gelişimi sürecinde, yol boyu ekipmanların yanı sıra araçüstü sistemlerde de ilerlemeler gerçekleşmiştir. 1869 yılında Amerika Birleşik Devletleri'nde demiryolu araçlarının belirli bir noktada durmasını sağlamak için raylara mekanik cihazlar yerleştirilmiştir. Kullanılan sistem "Train Stop" tren durdurma olarak isimlendirilmiştir. Demiryolu aracı durması gereken noktaya gelmediği sürece tren durdurma sistemi çalışmamaktadır.1870'lerde trenin hızını kontrol eden, referans değerlerin aşılması durumunda otomatik frenleme uygulayan sistemler kullanılmaya başlanmıştır.1900'lerde teknolojinin gelişimi ile birlikte otomatik tren koruma sistemleri de gelişim göstererek hız kontrolü yapabilen, frenleme ve tren takibi gerçekleştiren sistemler haline gelmiştir.1960'larda tren hareketlerini daha ayrıntılı inceleyen ve müdahale eden sistemler geliştirilmiştir. Avrupa ülkeleri arasında demiryolu taşımacılığının gelişmesi ile birlikte ülkelerin birbirleri ile uyumlu sinyalizasyon sistemleri geliştirilmesi bir zorunluluk haline gelmiştir. Bu nedenle Avrupa'da (ETCS) Avrupa Tren Kontrol Sistemi adı verilen bir standart otomatik tren koruma sistemi geliştirilmiştir. Ülkemizde de ETCS yanı sıra ATS adı verilen otomatik tren durdurma sistemi kullanılmaktadır. Bu tezin temel amacı, ülkemizde kullanımda olan ATS "Otomatik Tren Durdurma" sisteminin hemzemin geçit bölgelerinde de koruma sağlaması için ilave fonksiyonlar eklenmesini önermek ve bu önerilen sistemin petri ağları kullanılarak tasarımının yapılmasıdır. Önerilen model için petri ağları ile PLC kodu oluşturularak uygulama devresi ile test edilmiştir.
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ÖgeNumerical investigation of running dynamics of a freight wagon bogie with variable gauge wheels(Graduate School, 2022)Many innovations have been made on the basis of vehicles, rails and track structure in railway systems, which are of great importance for humanity. One among of a vast, axle groups called bogies are used to increase the performance of tractive and hauling stock to adapt curves on railway tracks. Thanks to bogies, the wheels provide a better positioning to the rails during their movements. The distance between two rails on railway line varies among various countries and regions around the world. The wheels on the vehicles also have to change and adapt to track according to this track gauge if the start and final points of the intended travel are on different gauge stations. Therefore, there is an additional labour and time loss in the track gauge changing situations of vehicles on railway routes passing over two different gauge. Variable gauge bogies are one of the best solutions to minimizing the cost and time of adaptation. This thesis aims to examine the running behaviour of a bogie design with variable gauge wheels using Numerical Multibody Dynamics Analysis. Wheel-rail interactions and many inter-vehicle interactions can be simulated with multibody simulation software platforms. A conventional three-piece bogie and the new design bogie are analyzed and compared in terms of stability, twisted track analysis and bogie yaw resistance according to the specified standards. "Method 1" was applied to the twisted track and the Nadal criteria were examined. The running safety was checked by staying below the limit values in the standard. On-track dynamic tests were performed only for the new design bogie. These dynamic tests were analyzed separately for various combinations of loading and vehicle length conditions using four differend classes of track according to their curve radii. The variable gauge distance bogie was also tested in two separate track gauges of 1435 mm and 1520 mm, as in the previous tests. Some parts of the studied bogie design were modeled in CATIA V5. In addition, wheel profile, rail profile, tracks in three-dimensional space, wheel-rail pairs and contacts are created in SIMPACK environment. Track and vehicle configurations where dynamic tests are carried out are modeled according to the requirements specified in EN 14363 and EN 16235 standards. An important recommendation was made to the design while performing all the tests. When the proposed design for the bogie was modeled exactly, derailment was observed in the wheels inside the curves. The problem has been solved by connecting the two inner axleboxes in the design to limit relative lateral movements to each other. As a result, while the new design exhibits a different character in terms of stability, it succesfully met the criteria examined in this study in terms of running safety of freight wagons.
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ÖgeBIM adoption and implementation in metro projects(Graduate School, 2022-01-19)The adoption of Building Information Modeling (BIM) is rather a newly explored arena, and this is a challenge of its own for the AECO industry. BIM implementation is still a challenge for the Turkish construction industry. BIM has been implemented for seven years in different metro lines with different stakeholders. However, such knowledge has not yet been analyzed in detail, even though these are Turkey's first BIM mandated projects. The thesis aims to determine the state of the art in BIM adoption and implementation processes in metro projects in Turkey and describe characteristic features, challenges, barriers, benefits and lessons-learned of BIM implementation in six real life metro projects in İstanbul. To achieve this aim, two detailed surveys and interviews are conducted. The first survey is conducted with 279 professionals to measure the BIM awareness of all technical staff in the metro projects. The second survey is conducted with 164 professionals to understand the level of the BIM application as perceived by the project participants, who are actively using BIM in their daily work. In addition, 37 in-depth interviews with experts are conducted to find the barriers encountered and describe the level of adoption in metro projects. This thesis analyzes the challenges as well as the barriers related to BIM implementation in addition to the gaps in the adoption of BIM in six real-life metro projects. The key three barriers detected i.e. 1) cultural and induvial barriers to BIM adoption in metro projects: "resistance to change (cultural/staff)", "lack of awareness" and "the need for a cultural change"; 2) economical, technological and leadership barriers to BIM adoption in metro projects: "lack of in-house expertise/skilled personnel shortage", "lack of training/education programs in universities" and "companies' lack of a strategy for the transition to BIM"; and 3) political and legal barriers to BIM adoption in metro projects: "lack of project delivery systems and organizational structures adapted to BIM", "lack of national standard, procedures and guidelines" and "lack of guidance for BIM implementation and utilization". This thesis describes the state of the art in BIM adoption and implementation in metro projects in Turkey. Further studies are needed to establish and enhance large-scale BIM adoption in the Turkish construction industry.